The invention relates to a dual cover system with a clamping closure mechanism for the gas tight closure of a container used particularly for containing radioactive or toxic waste materials, wherein the cover and the container opening have a round or polygonal shape and the cover includes a locking mechanism with clamping devices which are arranged at the circumference of the cover and coupled by the locking mechanism for synchronous operation.
Such so-called dual cover systems are used for closing containers for the containment of radioactive and toxic waste materials. For the transfer of the waste material from a storage containment to such a container, the container is coupled with its cover to the bottom cover of the containment such that the container cover and the containment cover are interconnected in a gas-tight manner to form a so-called double cover. This double cover can be moved as a unit into the containment after the container has been joined to the containment in a gas-tight manner. The waste material can then be transferred from the containment to the container and the transfer opening can again be closed after completion of the waste material transfer to the container. The double covers are then uncoupled and the container can be removed from the containment. During this procedure, only the inner surface areas of the containment and the container covers were exposed to the contaminated waste material, so that, after the uncoupling of the container cover from the containment cover the outer surfaces of the container and its cover are not contaminated.
However for the operation of the dual cover, the closure mechanisms of the two covers have to be coupled and they must be operated from the containment side. For this reason, the cover of the container is provided at its upper side, remote from the container, with a central engagement head for a form-locking reception by a gripping structure on the cover of the containment. For the release and the locking, the engagement head includes a collar stud as a component of the clamping closure mechanism, which is supported so as to be axially movable against the force of a spring. When the collar stud is not pressed inwardly the force of the spring causes a locking of the cover in the container opening by way of the spring force. The cover can be unlocked by pressing the collar stud inwardly against the force of the spring.
DE 34 25 979 C2 discloses a container cover with a central grasping head and a collar stud axially movably supported in the grasping head. The cover is provided with a clamping closure mechanism with several clamping devices which are arranged at the container side of the cover distributed over the cover circumference and are coupled by way of the clamping closure mechanism so that they are actuated to move outwardly in a synchronous manner. For the release, the collar stud is pressed into the grasping head, which engages a rigid support arm carrier, that extends parallel to the cover on the container side thereof. At the ends of the support arms, levers are pivotally supported so that they can be pivoted outwardly. The levers extend through openings in the cover and are concurrently moved outwardly by the relative movement of the support arm carrier and the cover when the collar stud is released or they are retracted when the collar stud is pushed inwardly. For the form fitting reception of the levers, the container includes a circumferential groove. During the locking and release movements however forces are generated which, in the area of the clamping structures, result in increased friction and therefore in relatively high force requirements for the operation of the double cover system.
It is the object of the present invention to provide a cover of a container as a component of a dual cover system, which is provided with a optimized clamping arrangement with low friction forces. The operating arrangement for the optimized clamping system also should be easy to manufacture accurately and provide for highly reliable sealing of the closed container.